Fix rotated coordinate grids and tas and pr for CORDEX datasets

[sloosvel]

Description

This PR adds metadata fixes for CORDEX data, that may break the checker or the concatenation of historical+scenario data, as well as fixing a bug that prevented the loading of the X-hourly tables in the CORDEX project. It also solves issues with rotated coordinate grids using the py-cordex package to access the correct grid information per each domain.

Closes #1764

Link to documentation:

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[zklaus]

I haven't looked at the fixes yet, but this looks great! Thanks for the work. I left a few minor comments and I have one more that I couldn't attach to any code:

Most __init__.py files have a short oneliner at the top, but tests/integration/cmor/_fixes/cordex/__init__.py is empty. Should we add the usual one-liner also there?

[sloosvel]

Ok, I think I addressed everything @bouweandela

[bouweandela]

Thanks for the great work @sloosvel @pepcos and @zklaus 🥳 Really awesome that we're finally getting CORDEX to work!